1 | /* |
2 | * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) |
3 | * Licensed under the GPL |
4 | */ |
5 | |
6 | #include <signal.h> |
7 | #include <kern_util.h> |
8 | #include <longjmp.h> |
9 | #include <sysdep/ptrace.h> |
10 | #include <generated/asm-offsets.h> |
11 | |
12 | /* Set during early boot */ |
13 | static int host_has_cmov = 1; |
14 | static jmp_buf cmov_test_return; |
15 | |
16 | static void cmov_sigill_test_handler(int sig) |
17 | { |
18 | host_has_cmov = 0; |
19 | longjmp(cmov_test_return, 1); |
20 | } |
21 | |
22 | void arch_check_bugs(void) |
23 | { |
24 | struct sigaction old, new; |
25 | |
26 | printk(UM_KERN_INFO "Checking for host processor cmov support..." ); |
27 | new.sa_handler = cmov_sigill_test_handler; |
28 | |
29 | /* Make sure that SIGILL is enabled after the handler longjmps back */ |
30 | new.sa_flags = SA_NODEFER; |
31 | sigemptyset(&new.sa_mask); |
32 | sigaction(SIGILL, &new, &old); |
33 | |
34 | if (setjmp(cmov_test_return) == 0) { |
35 | unsigned long foo = 0; |
36 | __asm__ __volatile__("cmovz %0, %1" : "=r" (foo) : "0" (foo)); |
37 | printk(UM_KERN_CONT "Yes\n" ); |
38 | } else |
39 | printk(UM_KERN_CONT "No\n" ); |
40 | |
41 | sigaction(SIGILL, &old, &new); |
42 | } |
43 | |
44 | void arch_examine_signal(int sig, struct uml_pt_regs *regs) |
45 | { |
46 | unsigned char tmp[2]; |
47 | |
48 | /* |
49 | * This is testing for a cmov (0x0f 0x4x) instruction causing a |
50 | * SIGILL in init. |
51 | */ |
52 | if ((sig != SIGILL) || (get_current_pid() != 1)) |
53 | return; |
54 | |
55 | if (copy_from_user_proc(tmp, (void *) UPT_IP(regs), 2)) { |
56 | printk(UM_KERN_ERR "SIGILL in init, could not read " |
57 | "instructions!\n" ); |
58 | return; |
59 | } |
60 | |
61 | if ((tmp[0] != 0x0f) || ((tmp[1] & 0xf0) != 0x40)) |
62 | return; |
63 | |
64 | if (host_has_cmov == 0) |
65 | printk(UM_KERN_ERR "SIGILL caused by cmov, which this " |
66 | "processor doesn't implement. Boot a filesystem " |
67 | "compiled for older processors" ); |
68 | else if (host_has_cmov == 1) |
69 | printk(UM_KERN_ERR "SIGILL caused by cmov, which this " |
70 | "processor claims to implement" ); |
71 | else |
72 | printk(UM_KERN_ERR "Bad value for host_has_cmov (%d)" , |
73 | host_has_cmov); |
74 | } |
75 | |